You have reached the maximum number of report subscriptions Error

Hi. We use smart lists for bounce, open and click reports for our email campaigns. We've been receiving an error ("You have reached the maximum number of report subscriptions") when attempting to set up subscriptions to these smart list reports. I've deleted all non-active smart list subscriptions and even the smart list reports themselves, but this hasn't solved the issue. I can usually add in a few smart listsubscriptions on Monday morning (after a weekend system refresh maybe?), but by Tuesday can only add a max of 2 and then no more until the following Monday. Any ideas/suggestions on how to remedy this would be greatly appreciated. Thanks!